Michael L. Sullivan mlsulliv at facstaff.wisc.edu
Mon Sep 16 14:43:42 EST 2002

Just a cautionary note on quantifying northerns using the DIG 
system-- the linearity of the response is not very good-- at least 
not in my hands when I compared side by side with radioactivity a few 
years ago (at the request of my Roche sales rep).  While radioactive 
probes and quantifying with a phosphoimager gave a linear response 
over more than 2 orders of magnitude, the dig-response was not even 
linear over an order of magnitude.  So, although singals can be 
quantified with DIG, I think it really requires the use of standards 
and/or dilution series for accurate results.  I'd be interested to 
hear if anybody's experienced anything different.


>I am having trouble with background on my Northern Blots.  The first 
>few times I used the system it worked great, lately though my films 
>havew been peppered with tiny spots.  As I am trying to quantitate 
>the bands this has become quite a problem.  I think that I have 
>tried everything.  Changing membranes, spinning down the Anti-DIG 
>antibody, being careful not to let the blot dry out....any ideas??


Michael L. Sullivan, 
U.S. Dairy Forage Research Center
1925 Linden Drive West
Madison WI, 53706

(608) 264-5144 Phone
(608) 264-5147 Fax

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